As you've said so often, the HABIT is much more important than the actual activity. I rather wish you'd made SG a sub-category under something like "14 minutes of intense movement" or the like. (There's got to be a clever overall name.)

And yes, I do it "seasonally" - it's the exercise version of an "intelligent dietary default." I like classes, and they normally fit into my routine well... I just have to re-create a routine when they're not available.